Hand-held dataform reader having multiple target area illumination sources for independent reading of superimposed dataforms

ABSTRACT

A portable data collection device having a modular imaging-based dataform reader. The dataform reader is adapted to independently read first and second overlying dataforms, the first dataform is imaged and decoded when illuminated by radiation having a first wavelength and the second dataform is imaged and decoded when illuminated by radiation having a second wavelength. Control and selection circuitry is electrically coupled to an imaging assembly and an illumination assembly to actuate the imaging assembly and selectively energize a first illumination source which generates radiation having a first range of wavelengths to image and decode the first dataform while a second illumination source is deenergized and to actuate the imaging assembly and selectively energize the second illumination source which generates radiation having a second range of wavelengths to image and decode the second dataform while the first illumination source is deenergized.

FIELD OF THE INVENTION

The present invention relates to a portable data collection deviceincluding an imaging-based dataform reader and, more particularly, to aportable data collection device including an imaging based dataformreader utilizing multiple target area illumination sources forindependent reading of superimposed dataforms.

BACKGROUND OF THE INVENTION

Portable data collection devices are widely used in manufacturing,service and package delivery industries to perform a variety of on-sitedata collection activities. Such portable data collection devices ofteninclude integrated bar code dataform readers adapted to read bar codedataforms affixed to products, product packaging and/or containers inwarehouses, retail stores, shipping terminals, etc. for inventorycontrol, tracking, production control and expediting, quality assuranceand other purposes. Various bar code dataform readers have been proposedfor portable data collection devices including laser scanners and onedimensional (1D) charge coupled device (CCD) imaging assemblies, both ofwhich are capable of reading 1D bar code dataforms, that is, bar codesconsisting of a single row of contrasting black bars and white spaces ofvarying widths. Both laser scanners and CCD imaging assemblies are alsocapable of reading a “stacked” two dimensional (2D) bar code dataforms,such as PDF417, which is comprised of a plurality of adjacent rows ofbar code data. The stacked 2D bar code PDF417 includes row indicatorpatterns utilized by the dataform reader for vertical synchronization topermit reading successive rows of bar code data.

A two dimensional (2D) imaging based dataform reader has been proposedin U.S. Pat. No. 5,702,059, issued Dec. 30, 1997 and entitled “ExtendedWorking Range Dataform Reader Including Fuzzy Logic Image ControlCircuitry.” The 2D dataform reader disclosed in U.S. Pat. No. 5,702,059,which is assigned to the assignee of the present application, includesan imaging assembly having a two dimensional array of photosensorsadapted to read 2D bar code dataforms (e.g., PDF417, SuperCode, etc.)with vertical synchronization row indicator patterns as well as matrixdataforms (e.g., MaxiCode, DataMatrix, etc.) which do not includevertical synchronization patterns. The individual photosensorscorrespond to image picture elements or pixels of the resulting imagegenerated with the photosensors are read out after an exposure period orperiods. The 2D dataform reader disclosed in U.S. Pat. No. 5,702,059utilizes an open loop feedback control system including fuzzy logiccircuitry to determine proper exposure time and gain parameters for acamera assembly. U.S. Pat. No. 5,702,059 is incorporated in its entiretyherein by reference.

Two dimensional and matrix dataforms have a greater density of encodeddata per unit area than 1D dataforms. However, even with 2D and matrixdataforms, there are limitations on the amount of data that can beencoded in a dataform applied to or imprinted on an item. First, thereare limitations on the area of a product or a product's packaging wherea label imprinted with a dataform may be affixed or where a dataform maybe directly imprinted. For certain items, any portion of the item may beacceptable for application of a dataform, thus, the acceptable area fordataform application is limited to the size of the item. However, forother items, the acceptable area for application of a dataform may belimited to a certain region having a generally flat surface suitable forlabel application or imprinting of a dataform. Second, a dataform readeris limited by a minimum cell size required by the reader. The minimumcell size of a dataform reader is the required size of the smallestindividually readable portions of a dataform to be read by the dataformreader. If the minimum cell size of a dataform is less than the minimumcell size capable of being read by the dataform reader, successfuldecoding of the dataform is not possible.

In an imaging based dataform reader, the minimum cell size capable ofbeing read is a function of a number of factors including the opticassembly and the illumination assembly of the reader. Generally, thesmaller the minimum cell size required to be read by a dataform reader,the better the quality of the optics of the optic assembly will be needto properly focus a non-distorted image of the target area of the readeronto the photosensor array. Consequently, the smaller the minimum cellsize that is required to be read, generally, the more expensive theoptic assembly will be. Similarly, the smaller the minimum cell sizethat is required to be read, the more powerful and more focused theillumination assembly must be to provide an adequate intensity ofillumination across the entirety of the target area of the reader.Again, the smaller the minimum cell size that is required to be read,generally, the more expensive the illumination assembly will be.

What is need is a method of generating a dataform having a high densityof encoded data per unit area of the dataform but also having anacceptably large minimum cell size so that the need for an expensiveoptic assembly and illumination assembly to read target dataforms isameliorated. What is further needed is a dataform reader capable ofreading such a dataform without undue expense or the necessity ofradically changing the imaging assembly from what is known in the art.

SUMMARY OF THE INVENTION

In accordance with this invention, a portable data collection device isprovided with a two dimensional imaging assembly including a modularboard camera providing for independent reading, that is, imaging anddecoding, of superimposed dataforms. The dataform reader is providedwith a targeting and illumination assembly comprising two illuminationor radiation sources, each illumination source providing illumination ina different range of the electromagnetic spectrum. In a first preferredembodiment, the first illumination source provides illumination in thevisible range, e.g., radiation having a wavelength range centered atabout 6600 Angstrom or 660 nanometers (nm.) corresponding to the visiblespectrum of light. The second illumination source provides illuminationin the ultraviolet range of the electromagnetic spectrum, e.g.,radiation having a wavelength range centered within the ultravioletrange which extends between about 200 Angstrom or 20 nm. to 3800Angstrom or 380 nm.

The superimposed dataforms are printed on a substrate in a dataformarea. The dataform area may be a label which is affixed to a product ora product's packaging. In such a case, the dataform area substrate onwhich the superimposed dataforms are printed would be the labelmaterial. In other cases the superimposed dataforms may be imprinteddirectly on an area of the product or the product's packaging. In thesecases, the dataform area substrate would be the portion of the productor product packaging where the dataforms are printed. In accord with thepresent invention, two superimposed dataforms will be printed on asubstrate in the dataform area. A first dataform will be printed on thesubstrate in the dataform area using a first pigment or ink for theprinted cell portions of the first dataform and a second dataform willbe printed on substrate in the dataform area using a second pigment orink for the printed cell portions of the second dataform.

The ink used for the printed cell portions of the first dataform is avisible, non-carbon ink, that is, ink that absorbs light in the visiblespectrum and does not absorb ultraviolet light. The ink used for theprinted cell portions of the second dataform is an ultraviolet activeink, that is, ink that fluoresces upon being illuminated by ultravioletlight. When ultraviolet active ink fluoresces, it emits lights in thevisible spectrum.

The imaging assembly of the present invention includes a modular boardcamera assembly having a two dimensional (2D) photosensor array, anoptic assembly for focusing an image of the target area onto thephotosensor array and the illumination assembly. In addition toproviding multiple illumination sources to successively illuminate thetarget area, the targeting and illumination assembly also includes atargeting assembly to provide targeting illumination for focusingvisible targeting illumination on the target area to aid a user inaiming the device.

In the preferred embodiment, the modular board camera assembly includescircuitry generating an analog composite video signal. The 2Dphotosensor array is a charge coupled device (CCD) comprised of a twodimensional matrix of photosensors. The composite analog video signalgenerated by the modular board camera assembly represents successiveimage frames of the imaging assembly target area. The composite videosignal is converted by signal processing circuitry to a stream of eightbit digital gray scale values.

Upon instituting a dataform reading session, the targeting illuminationassembly and the first visible illumination source are alternatelyenergized to enable the operator to aim the device and simultaneouslycapture image frames of the target area wherein the target area isuniformly illuminated and does not include “hot spots” of illuminationin the target area caused by the narrowly focused targetingillumination. Reflected illumination from the dataform corresponding tothe pattern of the first dataform is focused onto the photosensor array.To avoid image distortion, the targeting illumination assembly is turnedoff so that image frames without reflected targeting illumination aregenerated. Decoding will be attempted on such a non-distorted imageframe.

A portion of the set of gray scale values corresponding to the firstcaptured image frame is converted by binarization and zoning circuitryinto a set of binary (0,1) values in accord with a binarizationalgorithm. Working from a center of the image area outwardly, thecircuitry identifies the binary values corresponding to the firstdataform. The binary values corresponding to the imaged visible lightdataform are operated on by cell extraction circuitry. The cellextraction circuitry generates cell extraction values which correspondto an image of the first dataform area. Decoding circuitry then operateson the cell extraction values to decode the first dataform.

Upon successful imaging and decoding of a captured image frame having animage of the first dataform, the first illumination source isdeenergized and the second ultraviolet illumination source is energized.As with the first illumination source, the second ultravioletillumination source and the targeting illumination assembly arealternately energized and to enable the operator to aim the reader andsimultaneously capture image frames of the target area wherein thetarget area is uniformly illuminated and does not include “hot spots” ofillumination in the target area caused by the narrowly focused targetingillumination. The ultraviolet light causes the ultraviolet active inkportions of the dataform to fluoresce and emit visible illumination.This illumination pattern resulting from the fluorescence corresponds toa “negative” of the pattern of the second dataform. The illuminationpattern is focused onto the photosensor array. Once again, to avoidimage distortion, the targeting illumination assembly is turned off sothat image frames without reflected targeting illumination are generatedand decoding will be attempted on such a non-distorted image frame.

As before, the binarization and zoning circuitry convert a portion ofthe set of gray scale values corresponding to the second captured imageframe into a set of binary (0,1) values in accord with the binarizationalgorithm. Working from a center of the image area outwardly, thecircuitry identifies the binary values corresponding to the imaged UVlight dataform. The binary values corresponding to the UV light dataformare operated on by the cell extraction and the decoding circuitry, asset forth above, to decode the UV light dataform. Upon successfulimaging and decoding of a captured image frame having an image of thesecond dataform, the second illumination source is deenergized.

These and other objects, features and advantages of the invention willbecome better understood from the detailed description of the preferredembodiments of the invention which are described in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a two dimensional compositematrix dataform imprinted on a label, the composite matrix dataformcomprised of two superimposed two dimensional matrix dataforms;

FIG. 2 is a schematic representation of a first dataform of thecomposite dataform of FIG. 1;

FIG. 3 is a schematic representation of a second dataform of thecomposite dataform of FIG. 1;

FIG. 4 is a schematic representation of the composite dataform of FIG. 1showing the ink or combination of inks applied to each cell;

FIG. 5 is a perspective view of a portable data collection device of thepresent invention;

FIG. 6 is a top view of the portable data collection device of FIG. 1;

FIG. 7 is a front elevation view of the portable data collection deviceof FIG. 1 as seen from a plane indicated by the line 7-7 in FIG. 6;

FIG. 8 is a perspective view of a modular camera assembly of an imagingassembly of the portable data collection device of the presentinvention, the modular portion shown imaging a target dataform affixedto a target item;

FIG. 9 is an exploded perspective view of the modular camera assembly ofFIG. 8;

FIG. 10 is a side elevation view of the modular camera assembly of FIG.8 with an upper half of the housing removed;

FIG. 11 is a top plan view of a the modular camera assembly of FIG. 8with an upper half of the housing removed as seen from a plane indicatedby the line 11—11 in FIG. 10;

FIG. 12 is a top plan view of a lower half of the modular cameraassembly housing as seen in FIG. 11 with the modular camera assemblycomponents removed;

FIG. 13A is a sectional view of the lower half of the modular cameraassembly housing as seen from a plane indicated by the line 13A—13A inFIG. 12;

FIG. 13B is another sectional view of the lower half of the modularcamera assembly housing as seen from a plane indicated by the line13B—13B in FIG. 12;

FIG. 14 is a schematic representation of a plurality of lens of an opticassembly of the modular camera assembly;

FIG. 15 is a view, partially in side elevation and partially in sectionof the optic assembly of the modular camera assembly;

FIG. 16 is a front elevation view of the optic assembly of the modularcamera assembly as seen from a plane indicated by the line 16—16 in FIG.15;

FIG. 17 is a rear elevation view of the optic assembly of the modularcamera assembly as seen from a plane indicated by the line 17—17 in FIG.15;

FIG. 18 is an exploded perspective view of a targeting and illuminationassembly of the modular camera assembly of the imaging assembly of thepresent invention;

FIG. 19 is a perspective view of a lens array or front panel of theillumination assembly of FIG. 18;

FIG. 20 is an exploded perspective view of a targeting optics of thefront panel of FIG. 19;

FIG. 21 is a front elevation view of the front panel of FIG. 19;

FIG. 22 is a back elevation view of the front panel of FIG. 19;

FIG. 23 is a sectional view of the front panel of FIG. 32 as seen from aplane indicated by the line 23—23 in FIG. 21;

FIG. 24 is a sectional view of the front panel of FIG. 19 as seen from aplane indicated by the line 24—24 in FIG. 21;

FIG. 25 is a sectional view of the front panel of FIG. 19 as seen from aplane indicated by the line 25—25 in FIG. 21;

FIG. 26 is a representation of a crosshair illumination patterngenerated by the illumination assembly of FIG. 18 superimposed on atarget two dimensional bar code dataform;

FIG. 27 is a representation of a separation of crosshair illuminationpatterns of two targeting optics of the illumination assembly of FIG. 18caused by imaging with the portable data collection device at a distancefrom a target object significantly different than a best focus positionof the optic assembly of the device;

FIG. 28 is a representation of an angular shift of crosshairillumination patterns of two targeting optics of the illuminationassembly of FIG. 18 caused by imaging with the portable data collectiondevice tilted such that the front panel is not substantially parallel toa surface of a target object;

FIG. 29A is one portion of a block diagram of selected circuitry of theportable data collection device of the present invention;

FIG. 29B is a second portion of a block diagram of selected circuitry ofthe portable data collection device of the present invention, the secondportion matching the first portion shown in FIG. 29A;

FIG. 30 is a representation of photosensors of the imaging assembly twodimensional photosensor array;

FIG. 31 is a representation of image pixels corresponding tophotosensors of the imaging assembly photosensor array; and

FIG. 32 is a flow chart for reading (imaging and decoding) of the twodataforms comprising the composite dataform.

DETAILED DESCRIPTION Superimposed Composite Dataform 10

Turning to the drawings, a composite dataform 10 in accordance with thepresent invention is shown in FIG. 1. The dataform 10 is printed on adataform area 11 (outlined in dashed line in FIG. 1) of a white or lightcolored label 12. Preferably, an opposite side of the label 12 includesan adhesive facilitating attachment of the label 12 to a product or aproduct's packaging 14. The dataform 10 is defined by a square matrix of9 by 9 cells or spaces (best seen in FIG. 4), each cell being square inshape. The dataform 10 is comprised of a pattern of inked and non-inkedcells that results from an overlying or superimposition of two dataforms16, 18 occupying the same dataform area 11.

For clarity, the first dataform is shown at 16 in FIG. 2 and anoverlying or superimposed second dataform shown at 18 in FIG. 3. Thedataforms 16, 18 are schematic representations of DataMatix dataforms.DataMatrix is a binary symbology of International Data Matrix, Inc. ofClearwater, Fla. and is described in U.S. Pat. No. 5,473,151 to Priddyet al. While DataMatrix dataforms are used to illustrate the principalsset forth here of generating and reading superimposed or overlyingdataforms, it should be appreciated that any dataform, i.e., onedimensional bar code dataforms such as Codabar, Code 39, Code 93, Code128, Interleaved 2 of 5, and UPC/EAN; two dimensional bar code dataformssuch as PDF417 and SuperCode; and matrix dataforms such as MaxiCode andDataMatrix are all amenable to the processes described herein.

The first dataform 16 (FIG. 2) is comprised of a pattern of 9 by 9square shaped cells which are either inked (dark in color) 20 ornon-inked (light in color) 22. An inked cell 20 is generated by applyingor imprinting a label area corresponding to the cell with a dark colorvisible ink or pigment that absorbs light or radiation in the visiblespectrum, specifically, light having a wavelength around 660 nm., whilea non-inked cell (light-colored cell) 22 results from an absence of inkapplied to the cell and, therefore, the light-colored label 12 showsthrough and reflects visible illumination. The ink used to imprint theinked cells 20 of the first dataform 16 is a non-carbon based dark orblack ink.

The second dataform 18 (FIG. 3) is also comprised of a pattern of 9 by 9square shaped cells which are congruent with the cells of the firstdataform 16. The cells of the second dataform 18 are either inked withan ultraviolet active ink 24 or non-inked 26. An ultraviolet active inkis an ink that fluoresces upon being exposed to ultraviolet radiation orlight. An inked cell 24 is generated by applying or imprinting a labelarea corresponding to the cell with the ultraviolet active ink while anon-inked cell 26 results from an absence of ink applied to the cell. Anacceptable ultraviolet active ink is product no. A109461 ink produced byUVP, Inc. of Upland, Calif. 91786. This ink has an excitation peakwavelength of 365 nm. (UV long) and an emission wavelength maximum at500 nm. (green color emission). The ink fluoresces when the ink isexcited by radiation or illumination having a wavelength of around 365nm. and emits radiation or illumination having a range of wavelengths,the wavelengths of the emitted radiation being centered about a value ofabout 500 nm. Another acceptable ultraviolet active ink is product no.16.5420 ink produced by VideoJet Corp. of Wood Gale, Ill. 60191-1073.This ink has an excitation wavelength range of 350-510 mn. and anemission wavelength range of 580-605 mm.

FIG. 4 shows a schematic representation of the pattern of inked andnon-inked cells of the combined dataform 10. The cell rows and columnsof the dataform 10 have been numbered. A code indicates whether eachcell is non-inked, imprinted with a dark, visible non-carbon ink, and/orimprinted with an ultraviolet active ink. For example, a cell labeled 28at the intersection of row 1, column 9 is imprinted with both thevisible ink and ultraviolet active ink. A cell labeled 30 at theintersection of row 2, column 3 is imprinted with visible ink only. Acell labeled 32 at the intersection of row 2, column 4 is imprinted withultraviolet ink only. Finally, a cell labeled 34 at the intersection ofrow 2, column 6 is imprinted with no ink.

Portable Data Collection Device 100

A portable, hand held data collection device in accordance with thepresent invention is shown generally at 100 in FIGS. 5-12. The portabledata collection device includes a housing 110 supporting a twodimensional (2D) charge coupled device (CCD) photosensor array imagingassembly 102. The imaging assembly 102 is capable of independentlyreading, that is, imaging and decoding each of the first and seconddataforms 16, 18 of the composite dataform 10 when the dataform 10 islocated within an imaging target area 104 of the imaging assembly 102.

The imaging assembly 102 includes a modular board camera assembly 200and signal and image processing circuitry 250 mounted on a control anddecoder board 252. The control and decoder board 252 is electricallycoupled to electronic circuitry 201 of the modular board camera assembly200.

The board camera assembly 200 includes an optic assembly 300 and atargeting and illumination assembly 400. The optic assembly 300 focuseslight from the target area 104 onto a two dimensional photosensor array202 of the modular board camera assembly 200 while the targeting andillumination assembly 400 includes an illumination assembly 410providing illumination of the target area 104 and a targetingillumination assembly 450 providing targeting illumination for to aid inaiming the device 100 at the dataform 10.

As indicated above, the target dataform 10 is imprinted on a label 12affixed to a product or product packaging 14 and the device 100 isappropriately aimed at the packaging 14 such that the dataform 10 iswithin the target area 104. The imaging assembly 102 of the presentinvention operates to independently image and decode the first andsecond dataforms 16, 18 comprising the target dataform 10 when theimaging assembly 102 is actuated and the dataform is in the target area104. The illumination assembly 410 of the present invention is novel inthat it includes two illumination sources, a visible light source 412and an ultraviolet light source 414.

As will be explained below, the first dataform 16 is imaged when thevisible light source 412 is energized to direct illumination on thetarget area 104 and the second dataform 18 is imaged when theultraviolet light source 414 is energized to direct illumination on thetarget area 104. The targeting and illumination assembly 400 alsoincludes the targeting illumination assembly 450 to aid in aiming thedevice 100 such that the dataform 10 is in the target area 104 of theimaging assembly 102 thereby permitting imaging of the first and seconddataforms 16, 18.

Configuration of the Portable Data Collection Device 10

The modular board camera assembly 200 and the control and decoder board252 are supported in the housing 110 of the portable data collectiondevice 100. The housing 110 which is fabricated of a durable,lightweight polymer material such as high strength polyvinyl chloride.The housing 110 defines an interior region 112. The housing 110 includesa gripping portion 114 sized to be grasped in the hand of an operatorand an angled snout 116 extending from the gripping portion 114. Withspecific reference to FIG. 12, the snout 116 includes an opening throughwhich a portion of the board camera assembly 200 extends. The controland decoder board 252 is supported within the gripping portion 114 ofthe housing 110. Also supported within the housing gripping portion 114is a power source 124 such as a rechargeable battery for supplyingoperating power to the circuitry of the portable data collection device100 including the signal and image processing circuitry 250 and theboard camera circuitry 201. The gripping portion also supports a radiomodule 140 which is coupled to an antenna 136 extending through anopening in an upper surface of the housing snout 116.

A dataform reading trigger switch or actuator 126 extends through anopening in the gripping portion 114. The dataform reading trigger 126 ispositioned to be depressed by an index finger of the operator while thegripping portion 114 of the housing 110 is held in the operator's hand.

The gripping portion 114 also includes a small opening through which adistal portion of an indicator light emitting diode (LED) 132 isvisible. The indicator LED 132 alternates between three colors. Thecolor green is displayed by the indicator LED 132 when the device 100 ison standby, ready for use. The color orange is displayed with the device100 has successfully completed an operation such as imaging and decodingthe target dataform 10. The color red is displayed when the device 100is not ready to perform an operation.

A serial data output port 138 also extends through an opening in thegripping portion 114. The port 138 permits downloading of data stored ina memory 140 (shown schematically in FIG. 29A).

Configuration and Operation of the Imaging Assembly 102

Referring to FIGS. 12 and 13, which show perspective and explodedperspective views of the modular board camera assembly 200 of theimaging assembly 102. It can be seen that the modular board cameraassembly 200 includes a housing 220 which supports the optic assembly300, the targeting and illumination assembly 400 and the board cameracircuitry 201. The board camera assembly circuitry 201 includes the twodimensional photosensor array 202 mounted on a surface 212 of a first,frontward printed circuit board 210. The printed circuit board 210 and asecond, rearward printed circuit board 214 support the board cameracircuitry 210. The board camera assembly 200, when actuated orenergized, generates a composite video signal 260 (shown schematicallyin FIGS. 29A and 29B).

The modular board camera assembly 200 includes the optic assembly 300extending from the first printed circuit board 210 which focuses animage of the imaging target area 104 onto the 2D photosensor array 202(shown schematically in FIG. 14). Specifically, light from the imagingtarget area 104 is focused by the optic assembly 300 onto an outwardlyfacing, light receiving surface 204 of the photosensor array 202. Thephotosensor array 202 is part of a surface mounted integrated circuit(IC) chip 206. The photosensor array IC chip 206 is supported in an ICchip support 208 which is disposed on the front surface 212 (FIG. 9) ofthe front printed circuit board 210.

Structure of Photosensor Array 202

The photosensor array light receiving surface 204 comprises an array of584 rows by 752 columns of light sensitive photosensors for a total of439,168 photosensors in the photosensor array 202. An image of theimaging target area 104 is focused on the light receiving surface 204.Light incident on a photosensor during an exposure period charges thephotosensor. Subsequent to the exposure period, the photosensor chargeis read out or discharged. The charge magnitude or voltage read out froma photosensor represents an integration of the intensity of the lightfrom the target area 104 focused on the photosensor over the exposureperiod.

Each photosensor of the photosensor array 252 corresponds to a pictureelement or pixel of a captured image field or frame. For example, arepresentation of the light receiving surface 204 of the photosensorarray is shown in FIG. 30. A photosensor labeled PH(1,1) is located atthe intersection of photosensor row 1 and photosensor column 1 of thephotosensor array 202. The range of photosensor rows ranges from 1 to582 and the range of photosensor columns ranges from 1 to 752 for atotal of 439,168 photosensors. The corresponding set of image pixels fora captured image frame is represented in FIG. 31. As can be seen fromcomparing FIGS. 30 and 31, the image pixel labeled P(1,1) in FIG. 31corresponds to the photosensor labeled PH(1,1) in FIG. 30. The imagepixel labeled P(582, 752) in FIG. 31 corresponds to the photosensorlabeled PH(582,752) in FIG. 30. The photosensors of the photosensorarray 202 are read out in a frame mode interlaced format which means ata time t1, photosensors in every other row of the photosensor array areread out (e.g., rows 1, 3, 5, . . . , 581) to generate a first capturedimage field comprising 219,584 image pixels. At a later time t2,photosensors in the other rows are read out (e.g., rows 2, 4, 6, . . . ,582) to generate a second captured image field comprising 219,584 imagepixels. The images represented in the first and second captured imagefields, when appropriately interlaced in a row by row fashion comprise afull captured image frame comprising 439,168 image pixels.

Imaging Target Area 104 and the Optic Assembly 300

The imaging target area 104 is defined by a field of view and a depth ofview of the modular camera assembly 200 and is represented in FIG. 8 bythe dimensions labeled “H” (for height of imaging target area 44) and“W” (for width of the imaging target area 44). The lenses of opticassembly 300 define both the field of view and the depth of view of thetarget area 152.

The optic assembly 300 of the present invention is specificallyconfigured to permit reading by the imaging assembly 102 of standarddensity dataforms having a minimum cell size of 6.6 mils (0.0066 in. or0.167 mm.). The minimum cell size of a dataform is defined as thesmallest dimension of a separately readable information conveyingportion of the dataform.

FIG. 14 shows a cross section of the camera assembly 38 with the opticassembly 300 focusing an image of the imaging target area 104 onto thephotosensor array 202. The performance of the portable data collectiondevice 100 is enhanced by the optic assembly 300 which enables imagingand decoding of dataforms with a minimum cell size of 6.6 mil (0.168mm.). The optic assembly 300 includes a shroud assembly 302 (FIGS. 9 and15) and a lens assembly LA (FIG. 14). The lens assembly LA includeslenses L1, L2, L3, L4 and a spacer member SP1 with a small centralaperture Al (1.17 mm. in diameter) all supported within an innercylindrical shroud 304 (best seen in FIG. 9). The lens assembly LA alsoincludes a lens L5 which is supported by an upper surface of thephotosensor array IC chip support 208. Thus, there are eleven opticsurfaces (including the portion of the spacer member SP1 defining theaperture A1) labeled 310, 312, 314, 316, 318, 320, 322, 324, 326, 328,330 in FIG. 14. The outer optic surface 310 of the outermost lens L1 ofthe optic assembly 300 includes an ultraviolet filter coating 340 whichblocks ultraviolet illumination from passing through the optic assemblyand permits only light in the visible spectrum to be focused on thephotosensor array 202.

The shroud assembly 302 also includes a lock nut 340 and an outer shroud342. The lock nut 340 includes internal threads 344 which thread ontoexternal threads 346 of the inner shroud 304. When the lock nut 340 isproperly positioned on inner shroud threads 346, the inner shroud 304 isthreaded into internal threads 348 of the outer shroud 342. Whenassembled, the forward facing surface 350 of the lock nut 340 abuts aback surface 160 b of a printed circuit board 160. As will be explainedbelow, the outer shroud 342 is securely held in place by a secondsupport 182 of the upper and lower housing portions 141, 142 of theboard camera modular housing 140 thereby insuring a proper perpendicularangle relationship between an optical axis through the optic centers ofeach of the lenses L1, L2, L3, L4 and the outward facing, lightreceiving surface 204 of the photosensor array 202.

Additionally, the lock nut 340 facilitates precise positioning of thelenses L1, L2, L3, L4 of the lens assembly LA with respect to thelongitudinal displacement of the lenses along an optical axis labeledA—A in FIG. 11. The precise positioning of the lenses L1, L2, L3, L4, L5with respect to the photosensor array 202 permits the sharpest possibleimage of the target dataform 10 to be directed on the center point CP ofthe light receiving surface 404 of the photosensor array 202. As canbest be seen in FIG. 15, an O-ring 352 is disposed in a annular groovein the outer surface of the inner shroud 304. The O-ring 352 sealsagainst a central opening 720 of the lens array 62 to prevent externalcontaminants from entering the interior region 146 of the modularhousing 140.

Turning to FIG. 14, based on the distance between the optic assembly 300and the photosensor array 202, for a given dataform minimum cell size ordimension, there exists a best focus position S2 in front of theforward-most surface 90 of the lens L1 of the optic assembly 300 atwhich an image of the target dataform 10 in the imaging target area 104will be focused sharpest on a center point CP of the light receivingsurface 204 of the photosensor array 202. The image sharpness graduallydegrades as the target dataform 10 is moved from the best focus positioninwardly towards a near field cut off distance S1 or away toward a farfield cut off distance S3. At the near field and far field cut offdistances S1, S3, the target dataform 10 having the specified minimumcell size is still capable of being decoded. However, at distances lessthan S1 or greater than S3, the imaging assembly 102 will no longer beable to decode the target dataform 10.

As noted above, the imaging target area 104 is defined by an angularfield of view and a depth of the field of view. The horizontal andvertical angular field of view of optic assembly 300 is 32°(horizontal)×24° (vertical). This corresponds to a 40° diagonal field ofview. The horizontal angular field of view is shown schematically as anangle labeled with the designation A in FIG. 14. The depth of the fieldof view is defined by the near field and far field cut off distances S1and S3. The cut off distances are set forth below for a number ofdifferent dataform minimum cell sizes. At the S1 and S3 distances, adataform having the specified minimum cell size can still be decoded bythe imaging assembly 102. For a minimum cell size of 15 mil, the S2 bestfocus working distance is 140 mm. (5.5 in.).

The preferred optic assembly 300 includes four lenses L1, L2, L3, L4 andthe plastic spacer member SP1 separating lenses L2 and L3. The lensesL1, L2, L3, L4 and the spacer member SP1 are supported in the innershroud 304 of the shroud assembly 302. A flat lens L5 is mounted on anupper surface of the photosensor array IC chip 206 and overlies thelight receiving surface 204 of the photosensor array 202. Features ofthe optic assembly 300 include:

Field of view 32° (Horizontal) × 24° (Vertical) 82 mm. (3.2 in.) × 62mm. (2.4 in.) at a working distance of 140 mm. (5.5 in.) Minimum decodecell size 6.6 mil Ambient light total darkness to full sun lightSpectral range 400-700 nm. Focal length 8 mm. F-number 9 Image size 4.8mm. (Horizontal) × 3.6 mm. (Vertical) Resolution MTF > 50% @ 50 cyc/mmDistortion 1%

Image size refers to the size of the image projected onto thephotosensor array light receiving surface 204.

The working range of the optic assembly 300 with respect to reading 15mil. dataforms is as follows:

Min. Max working working Cell size distance distance Rotation S1 S3Pitch Skew 15 mil. 65 mm. 290 mm. 15° 15° 360° (2.5 in.) (11.5 in.)

The field of view or imaging target area 104 of the optic assembly 300at the best focus distance S2 of 140 mm. (5.5 in.) and at the minimumand maximum working distances S1, S3 are as follows:

Distance Width Height S1  37 mm. (1.5 in.)  28 mm. (1.1 in.) S2  82 mm.(3.2 in.)  62 mm. (2.4 in.) S3 166 mm. (6.5 in.) 123 mm. (4.9 in.)

The optic prescriptions for each of the optic surfaces of the opticassembly 300 are as follows:

Optic Radius of Surface Surface Curvature Diameter Share 310 10.093 mm. 7 mm. Concave 312 3.635 mm. 7 mm. Concave 314 6.995 mm. 7 mm. Convex 3165.834 mm. 7 mm. Convex 318 1.171 mm. 7 mm. Flat (Flat) Infinity -Pinhole diameter 320 25.116 mm.  7 mm. Concave 322 5.834 mm. 7 mm.Concave 324 13.499 mm.  7 mm. Convex 326 4.325 mm. 7 mm. Convex 328Infinity 7 mm. Flat (Flat) 320 Infinity 7 mm. Flat (Flat)

The distance between successive optical surfaces 310-320 is as follows:

Optic Surface Distance 310-312 0.529 mm. 312-314 0.609 mm. 314-316 2.389mm. 316-318 1.714 mm. 318-320 2.114 mm. 320-322 0.599 mm. 322-324 0.366mm. 324-326 2.482 mm. 326-328  7.27 mm. 328-330  0.60 mm.330-Photosensor  1.31 mm.

Where “Photosensor” is the light receiving surface 204 of thephotosensor array 202. The glass type for each lens L1, L2, L3, L4, L5of the lens assembly LA is as follows:

Lens GLASS TYPE REFRACTIVE INDEX L1 SF5 Schott 1.67270 L2 RAFD13 Hoya1.85540 L3 SF11 Schott 1.78472 L4 LAK21 Schott 1.64050 L5 BK7 Schott1.51289

The lenses L1, L3, L4, L5 are available from Schott Glass Technologies,Inc. of Duryea, Pa. The lens L2 is available from Hoya Corp USA, OpticsDivision located in San Jose, Calif.

Targeting and Illumination Assembly 400

The targeting and illumination assembly 400 includes the illuminationassembly 410 and the targeting assembly 450. The illumination assembly410 includes two illumination sources, the first or visible light source412 and the second or ultraviolet light source 414. When the imagingassembly 102 is energized by an operator depressing the trigger 126, thetargeting illumination assembly 400 is activated producing anillumination pattern (described below) to aid in aiming the device 100.The visible light source 412 is also energized to enable imaging of thefirst dataform 16 while the ultraviolet light source 414 remainsdeenergized. The visible light source 412 and the targeting illuminationassembly 450 are alternately energized.

The targeting illumination causes “hot spots” of high illuminationintensity in portions of the target area 104 and reflected glare. Thus,image frames generated when the targeting illumination is energized arenot suitable for decoding of the dataform 10 imaged therein. Imageframes generated when the targeting illumination assembly 450 isdeenergized and the first visible light source 412 is energized arecharacterized by uniformity of illumination intensity across the targetarea 104. Such image frames are suitable for decoding the first dataform16 of the dataform 10.

The cells of the dataform 10 imprinted with visible ink absorb thevisible illumination. The cells of the dataform 10 which are notimprinted with any ink (non-inked cells) reflect the illumination fromthe visible light source 412 because of the white color of the label 12.The ultraviolet active ink does not effect the reflectivity ofillumination in the visible spectrum. Therefore, cells of the dataform10 imprinted with only the ultraviolet active ink also reflect thevisible illumination emitted by the visible light source 412 just likethe non-inked cells.

Thus, the image focused on the photosensor array 202 when the dataform10 is in the target area 104 of the imaging assembly 102 corresponds tothe first dataform 16, that is, the image includes dark areascorresponding to cells of the dataform 10 having visible ink and lightareas corresponding to cells of the dataform having either no ink oronly ultraviolet active ink imprinted thereon. As mentioned above, thetargeting illumination assembly 450 is intermittently deenergized sothat a captured image frame to be processed and decoded does not haveany illumination “hot spots” and interfering reflected glare from thelabel 12.

After the image of the first dataform 16 is successfully processed anddecoded, the first or visible light source 412 is deenergized and thesecond or ultraviolet light source 414 is energized to enable imaging ofthe second dataform 18. As with the visible illumination source 412, theultraviolet light source 414 and the targeting illumination assembly 410are alternately energized milliseconds. Thus, an image frame capturedduring deenergization of the targeting illumination assembly does nothave any illumination “hot spots” or reflected glare and the imageddataform which is the second dataform 18 is suitable to be processed anddecoded. The cells of the dataform 10 imprinted with ultraviolet activeink fluoresce when exposed to the ultraviolet illumination and generateillumination in the visible spectrum. The non-ink cells of the dataform10 and the visible ink only cells of the dataform 10 reflect most of theillumination from the ultraviolet light source 414.

As discussed above, the outer optic surface 310 of the outermost lens L1of the optic assembly 300 includes a coating 340 that functions as anultraviolet light filter, that is, the coating blocks ultravioletillumination from passing through the optic assembly and permits onlylight in the visible spectrum to be focused on the photosensor array202. Thus, the visible light emitted by the fluorescence of theultraviolet active ink cells is focused on the photosensor array 202.Consequently, the image focused on the photosensor array 202 when thedataform 10 is in the target area 104 of the imaging assembly 102corresponds to a negative of the second dataform 16, that is, the imagefocused on the photosensor array 202 includes light areas correspondingto cells of the dataform 10 that are imprinted with the ultravioletactive ink and further includes dark areas corresponding to cells of thedataform 10 having either no ink or visible ink only.

It should be noted however, that in the first dataform 16, the darkcells corresponded to the cells of the dataform imprinted with the darkvisible ink and the light-colored cells corresponded to the non-inkedcells of the dataform. In the image of the second dataform 18 focused onthe photosensor array 202, the reverse is true, that is, thelight-colored cells corresponded to the cells of the dataform imprintedwith the ultraviolet active ink and the dark cells corresponded to thenon-inked cells of the dataform. That is why the image focused on thephotosensor array 202 is referred to as the negative of the seconddataform 18.

Image processing circuitry 285 (discussed below) of the imaging assembly102 takes this contrast reversal into account when decoding the image ofthe second dataform. As before, the targeting assembly 450 isintermittently deenergized so that a captured image frame to beprocessed and decoded does not have any interfering reflected glare fromthe label 12. The actuation and deactuation (turning on and off) ofcomponents of the imaging assembly 102 is performed by control andselection circuitry 284 (FIG. 29A) which is part of signal and imageprocessing circuitry 250 all of which operates under the control of amicroprocessor 251.

In FIG. 32, a flow chart is shown at 900 which sets forth the processingsets associated with reading the dataform 10, that is, sequentiallyimaging and decoding the first dataform 16 and the second dataform 18.Upon the operator depressing the dataform reading trigger 126, at step902, the imaging assembly 102 is actuated and, at step 903, thetargeting illumination is alternately energized with the visibleillumination source 412. Assuming the device 100 is properly aimed atthe dataform 10, at step 904, target area image frames including thefirst dataform 16 are captured. As noted above, only image framescaptured during periods when the targeting illumination was off aresuitable for processing and decoding. At step 905, a suitable imageframe is processed and an attempt is made to decode the imaged firstdataform 16.

If the first dataform 16 is decoded, at step 906, the visibleillumination source is deenergized and the ultraviolet illuminationsource 414 is alternately energized with the targeting illumination.Again assuming the device 100 is properly aimed at the dataform 10, atstep 908, target area image frames including the second dataform 16 arecaptured. As noted above, only image frames captured during periods whenthe targeting illumination was off are suitable for processing anddecoding. At step 909, a suitable image frame is processed and anattempt is made to decode the imaged second dataform 18. Upon successfuldecoding of the second dataform 18, at step 910, the imaging assembly102 including the targeting illumination and the ultravioletillumination source 414 are turned off and the LED 132 is energized todisplay an orange color to notify the operator that the reading of thedataform 10 has been successfully completed.

As is clear from the above explanation, the visible illumination source412, the ultraviolet light source 414 and the targeting illuminationassembly 450 are actuated or energized by the control and selectioncircuitry 284 on a mutually exclusive basis.

The first or visible illumination source 412 comprises four banks offour red light emitting diodes (LEDs) 466. The visible illumination LEDs466 emit red color illumination in the visible range at a wavelength ofapproximately 660 nm. Each bank of LEDs is focused through correspondingillumination optic portions 488 a, 488 b, 488 c, 488 d which project auniform intensity distribution of illumination across the imaging targetarea 104. Suitable red surface mount LEDs are available as Part No.MTSM735K-UR or MTSM745KA-UR from MarkTech Corporation of Lathar, N.Y.

The second or ultraviolet illumination source 414 comprises twominiature ultraviolet lamps 489 a, 489 b. As can best be seen in FIGS. 9and 18, the ultraviolet lamps 489 a, 489 b are mounted to the frontsurface 460 a of the printed circuit board 460, lamp 489 a being mountedhorizontally near the top of the front surface 460 a and the lamp 489 bbeing mounted horizontally near the bottom of the front surface 460 a.The lamps are connected to the printed circuit board front surface 460via relatively stiff supports 490. The supports 490 position theultraviolet lamps 489 a, 489 b away from the circuit board 460.Conductive leads 491 extending from one end of each lamp to the circuitboard front surface 460 a are used to energize the lamps.

The lamps 489 a, 489 b fit into horizonal cut outs in a lens array 700.Thus, when lamps 489 a, 489 b are energized, ultraviolet light is caston the target area. Extending from the lens array 700 into the cut outregion are curved reflectors 704 which aid in focusing the ultravioletillumination onto the imaging target area 104. Suitable miniatureultraviolet lamps 489a, 489b are available from JKL ComponentsCorporation of Pacoima, Calif. 91331. One suitable lamp is Part No.BF727-UV2 which has a peak spectral output at a wavelength of 254 nm.and is 27 mm. in length and 7 mm. in diameter.

The targeting assembly 450 also includes a targeting arrangementincluding targeting LEDs 482 a, 482 b, which, when energized, projectillumination through first and second targeting optics 484 a, 484 athereby generating a crosshair targeting illumination pattern CR to aidin aiming the device 100. To avoid image distortion, the targetingpattern CR is intermittently turned off by the imaging assembly 102 whenthe image frames of the imaging target area 104 are being captured. InFIG. 26, the crosshair illumination pattern CR is shown aimed at a 2Dbar code dataform 10′. The dataform 10′ is imprinted on a label 12′affixed to a product 14′.

The targeting and illumination assembly 400 includes a printed circuitboard 460 and the lens array 700. The lens array 700 functions as theouter or front panel of the modular camera assembly 200. The term “frontpanel” will be used interchangeably with the term “lens array”throughout. The lens array 700 is a single piece acrylic orpolycarbonate, preferably fabricated of PMMA (polymethyl methacrylate),and is positioned between the printed circuit board assembly 460 and thetarget area 104 (FIGS. 8 and 9) for directing the illumination from thefour banks of visible illumination LEDs 466 toward the target area 104.The visible illumination LEDs 466 are disposed on the front surface ofprinted circuit board 460 to direct illumination through the lens array700 towards the imaging target area 104.

The flexible printed circuit board 463, which route power to thetargeting LEDs 464 a, 464 b, is also electrically coupled to the circuitboard 460. The flexible printed circuit board 463 has a central u-shapedcut out region 463 c to provide clearance for the outer shroud of theshroud assembly 302. The targeting LEDs 464 a, 464 b, when energized,project targeting illumination through openings 468 in the circuit board460 and through targeting optics 722, 724 of the lens array 700 to formthe crosshairs light or illumination pattern CR which aids in aiming thedevice 100 at the target dataform 10.

Because the desired working range and field of view of the portable datacollection device 100 dictates that the optic assembly 43 have a large Fnumber (F# 9), the visible illumination assembly 410 must provideadequate illumination of the imaging target area 104 during the exposureperiod so that enough light is absorbed by the photosensor array 202 togenerate a suitably bright image. However, the exposure period isnormally limited to 0.01 seconds or less to minimize the smear effect ofan operator's hand jittering during a dataform reading session.Therefore, the illumination assembly 410 must provide adequateillumination to accommodate the large F# and short exposure time.

The printed circuit board assembly 460 includes printed conductors andconductive leads 196 including a power lead operative for supplyingpower to the illumination LEDs 466 and the ultraviolet lamps 489 a, 489b. Each illumination LED 466 provides illuminosity of 285 milli candela(mcd) over an angular illumination field of about 68 degrees. The smallfootprint of each illumination LED 466 enables four LEDs to be placed ina row measuring less than 14 mm. The printed circuit board assembly 460includes four banks of four illumination LEDs 466 totaling sixteenillumination LEDs providing at least 4560 mcd of uniform illuminationover the target area 104 at the best focus distance S2.

The lens array 700 includes four illumination optic portions 708 a, 708b, 708 c, 708 d (FIGS. 9 and 18) each of which are aligned with acorresponding bank of illumination LEDs 466. The illumination opticportions 708 a, 708 b, 708 c, 708 d direct a 68 degree angularillumination field from each illumination LED 466 into a uniform fieldhaving an angular field of view horizontally and vertically whichsubstantially corresponds to the angular field of view horizontally andvertically of the optic assembly 300 which defines the imaging targetarea 104.

Referring to FIGS. 23 and 25, which show a horizontal cross section(FIG. 23) and a vertical cross section (FIG. 25) through theillumination optic portions 708 a, 708 b, 708 c, 708 d, it can be seenthat each optic portion comprises a lens including four verticallyoriented cylindrical entry optic surfaces 716 extending from a back side717 (FIG. 23) of the lens array 700. One vertically oriented cylindricalentry surface 716 is positioned in front of a corresponding LED 466.

Each optic portion 708 a, 708 b, 708 c, 708 d also includes ahorizontally oriented cylindrical optic exit surface 718 extending froma front side 719 (FIG. 23) of the lens array 700. One horizontallyoriented cylindrical exit optic surface 718 is positioned, in front ofeach bank of four LEDs 466.

The vertically oriented cylindrical entry optic surfaces 716 define thehorizontal field of illumination and the horizontally oriented cylinders718 define the vertical field of illumination. This arrangement providesan even illumination intensity distribution across the target area 104.The 4560 mcd of illumination provided by the illumination LEDs 466 willprovide an illumination intensity in excess of 106 lux at the far fieldcut off distance S3 of 290 mm. (11.5 in.) for 15 mil minimum cell sizedataforms. The vertically oriented entry surfaces 716 have a radius ofcurvature of 1.50 mm. and a height I (FIG. 35) of 4.00 mm. while thehorizontally oriented exit surfaces 718 have a radius of curvature of3.0 mm. and a width J (FIG. 36) of 13.75 mm. Referring to FIGS. 21-23,suitable dimensions for the lens array 700 are as follows:

Label Description Dimension A Height of lens array 700 21.75 mm. B Widthof lens array 700 39.55 mm. C Diameter of center opening 12.00 mm. 720of lens array 700 D Height between middle of 14.13 mm. vertical entrysurfaces 716 E Thickness of lens array 700  1.95 mm.

Referring again to FIG. 18, the targeting and illumination assembly 400also includes a targeting arrangement or assembly to aid in aiming thedevice 100 at the target dataform 10; The targeting illuminationassembly 450 includes the targeting LED illuminators 464 a, 464 b, whichextend into apertures 468 in the printed circuit board assembly 460 and,when energized, project illumination into first and second targetingoptics 722, 724 respectively of the lens array 700. The first and secondtargeting optics 722, 724 are mirror images of each other and areidentical in configuration. Each targeting optic generates a crosshairpattern of illumination CR1, CR2 (seen in FIGS. 18 and 26) and if thetarget dataform 10 is at a proper distance for imaging, i.e., at thebest focus position S2 of the optic assembly 300, the crosshairs CR1,CR2 will coincide or overlap producing a single rectangular crossing orcrosshair pattern of illumination CR (FIGS. 18 and 26). The rectangularillumination pattern CR will have a height h of 62 mm. (2.4 in.) and awidth w of 82 mm. (3.2 in.) (FIG. 18) at the best focus position S2 (140mm.). The rectangular illumination pattern CR substantially correspondsto the target area 104 of the optic assembly 300 at the best focusposition S2. Of course, the rectangular illumination pattern CR will notbe a perfect intersecting line crosshair but rather will becharacterized by an illumination intensity distribution or patternhaving some visible “thickness” t (FIG. 18), but will nonetheless besuitable for aiming the device 100.

The first and second targeting optics 722, 724, which are identical inconfiguration, are shown in cross section in FIGS. 24 and 25. The firsttargeting optics 722 comprises a lens with an aspherical light entryoptic surface 726 and a segmented cylindrical light exit optic surface728. The second targeting optics 724 comprises a lens with an asphericallight entry optic surface 730, similar to the aspherical light entryoptic surface 726, and a segmented cylindrical light exit optic surface732, similar to the segmented cylindrical light exit optic surface 728.

The aspherical entry surfaces 726, 730 each have a diameter of 8 mm., aradius of curvature of 2.890 mm. and a conic constant of −2.534. Thesegmented cylindrical light exit surfaces 728, 732 each have an 8.0 nm.by 8.0 mm. square shaped outer perimeter. The segmented cylindricalsurface 728 is comprised of. four triangular shaped sections 740, 742,744, 746 (FIG. 21) while the segmented cylindrical surface 732 isdivided into four triangular shaped sections 750, 752, 754, 756, whereinthe optic surfaces of sections 740 and 750 are identical, the opticsurfaces of sections 742 and 752 are identical, the optic surfaces ofsections 744 and 754 are identical and the optic surfaces of sections746 and 756 are identical.

Upper and lower triangular sections 740, 744 comprise verticallyoriented cylindrical light exit optic surfaces. Left and righttriangular sections 742, 746 comprise horizontally oriented cylindricallight exit optic surfaces. Similarly, upper and lower triangularsections 750, 754 comprise vertically oriented cylindrical light exitoptic surfaces, while left and right triangular sections 752, 756comprise horizontally oriented cylindrical light exit optic surfaces.The vertically oriented cylindrical optic surfaces 740, 744, 750, 754have a radius of curvature of 25.00 mm. Similarly, the horizontallyoriented cylindrical optic surfaces have a radius of curvature of 25.00mm.

As can best be seen in FIG. 24, the horizontally and vertically orientedcylindrical optic surfaces 742, 746, 740, 744 are tipped at an angle cwith respect to a longitudinal axis L—L though the lens array 700 and,therefore, is also tipped at an angle c with respect to the target area104 (that is, parallel to the plane defined by the generally flat frontsurface 717 of the lens array 700). The tip angle c of the horizontallyoriented cylindrical optic surfaces 742, 746 shifts the horizontalposition of the illumination rectangle or targeting crosshair CR1(schematically shown in FIG. 18) generated by the first targeting optics722 such that it is horizontally centered in the target area 104 whilethe tip angle c of the vertically oriented cylindrical optic surfaces740, 744 shifts the vertical position of the targeting crosshair CR1generated by the first targeting optics 722 such that it is verticallycentered in the imaging target area 104. A suitable tip angle of c is9.83 degrees.

Similarly, as can also be seen in FIG. 24, the horizontally andvertically oriented cylindrical optic surfaces 752, 756, 750, 754 arealso tipped at an angle c which is preferably 9.83 degrees with respectto a longitudinal axis L—L though the lens array 700. Note that thedirection of tilt of the segmented cylindrical light exit surfaces 728,732 are the same in magnitude but opposite in a direction of tilt, thatis, the light exit surface 728 of the first targeting optics 722 slantsdownwardly to the left toward the front side 719 in FIG. 24, while thelight exit surface 732 of the second targeting optics 724 slantsdownwardly to the right toward the front side 719 in FIG. 37. Also notethat the two horizontally oriented light exit optic surfaces 718 whichwould be seen in FIG. 24 have been removed for clarity of the drawing.It should also be noted that FIG. 20 which shows the segmentedcylindrical light exit surface 732 as being comprised of four individualexploded “pieces” is only a representation to provide additional clarityas to the shape and tilt of the four light exiting surfaces 750, 752,754, 756. The lens array 700 is fabricated as a single piece and thetargeting optics 722, 724 and illumination optics 716, 718 are formed inthe single piece. The lens optics are not fabricated by “piecing”together individual optics as might be assumed in looking at FIG. 20.

Additional suitable dimensions, labeled on FIG. 24, for the asphericlight entry surfaces 726, 730, the segmented cylindrical light exitsurfaces 728, 732 of the lens array 700 are as follows

Label Description Dimension F Maximum extension of aspheric 1.75 mm.light exit surfaces 726, 730 from back side 717 of lens array G Distancebetween maxinium extension 5.25 mm. of aspheric light exit surfaces 726,730 and center of respective segmented light exit surfaces 728, 732along centerlines T-T H Distance between centerlines T-T 7.80 mm. andouter edge of lens array 700

Targeting Illumination Crosshairs CR1, CR2

As noted above, the best focus distance S2 is 140 mm. (5.5 in.). If thedevice 100 is oriented such that generally flat front surface 717 of thelens array 700 is substantially parallel to a surface of the targetdataform 10 and positioned at the best focus distance S2 from thetarget, then the targeting crosshairs CR1 and CR2 will coincide andgenerate the single targeting crosshair CR as shown in FIG. 26 having anapproximate height h of 62 mm. (2.4 in.) and an approximate width w of82 mm. (3.2 in.) which substantially corresponds to the target area 44height of 62 mm. and width of 82 mm. at the best focus position S2 of140 mm. (5.5 in.) in front of the optic surface 310 of lens L1.

If the device 100 is moved away from the best focus distance S2 withrespect to the target dataform 10, the targeting crosshairs CR1 and CR2will separate horizontally as shown in FIG. 27 thereby informing theoperator that the distance of the device 100 from the target dataform 10is not correct for best imaging or imaging and decoding. Finally, if thelens array 700 is not substantially parallel to a surface of the targetdataform 10, that is, the device 100 is tilted forward or backward froma position where the front surface 717 of the lens array or front panel700 is parallel to the target surface, the vertical portions of theillumination patterns of CR1 and CR2 will be angularly shifted ordisplaced as shown in FIG. 28, the greater the angle of tilt of thedevice 100, the greater will be the angular shifting of the verticalportions of the illumination patterns CR1, CR2.

As was noted above, the targeting LEDs 464 a, 464 b are alternatelyturned off by the imaging assembly control and selection circuitry 284to provide for capture of image frames not subject to possible imagedistortion caused by glare from the targeting LEDs reflecting off thetarget dataform 10.

Modular Camera Assembly Housing 140

The modular board camera assembly 200 is shown in FIGS. 8-13B. Suitableexterior dimensions for the two piece housing 140 of the board cameraassembly 200 are as follows:

Housing Label Dimension Height MH (FIG. 8) 1.02 in. (26 mm.) Width MW(FIG. 8) 1.65 in. (42 mm.) Length ML (FIG. 8) 1.57 in. (40 mm.)

The modular board camera housing 140 includes an upper portion 141 and asymmetrical lower portion 142. The upper and lower portions 141, 142 areadvantageously identically shaped and positioned symmetrically about apart line 144 and define an interior region 146 (FIG. 9) in whichcomponents of the modular camera assembly 200 are supported. Since theupper and lower portions 141, 142 are symmetrical, only the constructionof the lower portion 142 will be discussed with the understanding thatthe same construction and features are present in the mating upperportion 141. In this way, fabrication and assembly of the modular cameraassembly 200 is simplified because the housing portions 141, 142 areinterchangeable and, therefore, only one configuration needs to befabricated.

As can best be seen in FIGS. 9, 12, 13 a and 13 b, the housing lowerportion 142 includes a substantially flat base 150 and three side walls152, 154, 156 extending perpendicularly from the base 150. An innersurface of the side wall 152 includes two spaced apart slots 160 a, 162a extending from an upper edge 164 of the housing lower portion 142defined by the side walls 152, 154, 156 to an inner surface 166 of thebase 150. Similarly, an inner surface of the side wall 156 includesmatching spaced apart slots 160 b, 162 b extending from the upper edge164 of the housing lower portion 142 to the inner surface 166 of thebase 150.

The modular camera assembly 200 includes circuitry mounted on a set oftwo parallel, spaced apart front and rear printed circuit boards 210,214 affixed to a spacer element 215 (FIGS. 11 and 14). The slots 162 a,162 b receive and securely hold the rear printed circuit board 214 (FIG.11) while the slots 160 a, 160 b receive the front printed circuit board210. Mounted on a front surface 212 of the front printed circuit board210 is the 2D photosensor array IC chip 206. The optic assembly 300 mustbe precisely aligned with the photosensor array 202 to insure properimaging of the imaging target area 104. Spring-like projections 170 a,170 b (FIGS. 9 and 12) extend upwardly from the base inner surface 166.As can best be seen in FIG. 12, the projections 170 a, 170 b are spacedfrom their respective side walls 152, 156 but are still within regionsdefined by the slots 160 a, 160 b.

When the printed circuit boards 210, 214 are inserted in theirrespective slots 162 a, 162 b, 160 a, 160 b, the projections 170 a, 170b flex and push in a horizontal direction against a back side 213 (FIG.11) of the printed circuit board 210 in a direction labeled F to insurethe boards 210, 214 are securely held in place and the photosensor array202 is precisely located. Additionally, as can be seen in FIGS. 12 and13A, the slots 162 a, 162 b are tapered adjacent the base inner surface166.

The slots 162 a, 162 b become narrower near the base 150 thereby forcingthe printed circuit board 214 in the direction F. The taper of the slots162 a, 162 b combined with the projections 170 a, 170 b in the slots 160a, 160 b apply sufficient force to the printed circuit boards 210, 214so as to eliminate any “play” of the front and rear printed circuitboards 210, 214 in their respective slots.

The housing lower portion 142 also includes first and second supports172, 182 extending upwardly from a slightly raised portion 167 (FIG. 12)of the base inner surface 166. As can best be seen in FIGS. 9, 11 and12, the first support 172 includes a central portion 174 with asemicircular recess flanked by two outerlying portions 175 a, 175 bhaving smaller semicircular recesses. The central portion 174 supportsan outer shroud 342 of the optic assembly 300. The two smallerouterlying portions support respective targeting light emitting diodes473 a, 473 b of the targeting illumination assembly 450. The targetingLEDs 464 a, 464 b are cylindrically shaped and include enlarged diameterbase portions 465 a, 465 b (best seen in FIG. 11) which fit intoinwardly stepped semicircular recesses 176 a, 176 b of the outerlyingportions 175 a, 175 b. A first end portion 183 of the second support 182includes a semicircular recess which supports the outer shroud 342. Justinward of the end portion 183 is a portion 184 (FIGS. 12 and 13A)defining another semicircular recess having a slightly larger diameterthan the recess of the end portion 183. The portion 184 is sized toreceive an outwardly flared end portion 343 of the outer shroud 342 andthereby position it precisely with respect to the photosensor array 202.The outwardly flared end portion 343 of the outer shroud 342 includestwo small cut out portions 354 (only one of which can be seen in FIG.9). One of the cut out portions 354 fits onto a raised nub 185 of thesemicircular shaped portion 184 to prevent the outer shroud 342 fromrotating within the housing 240. The other cut out portion 354, ofcourse, fits onto an identical nub (not shown) of the upper housingportion 141 which is identical in shape and configuration to the lowerhousing portion 142.

As can best be seen in FIG. 13B, a second end portion 186 of the secondsupport 182 includes a rectangular shaped recess. Disposed between thesecond end portion 186 and the portion 184 is a portion 187 (FIGS. 12,13A and 13B) defining a rectangular shaped recess that is slightlysmaller size than the recess defined by the end portion 186. As can beseen in FIG. 11, the recess of the portion 184 receives an extendingportion of the photosensor array IC chip support 208. The photosensorarray chip support 208 is mounted to the front surface 212 of theprinted circuit board 210. The front surface 212 of the printed circuitboard 210 abuts the second support end portion 186 and, thus, the lightreceiving surface 204 of the photosensor array 202 is preciselypositioned with respect to the support and with respect to the opticassembly 300 both in terms of a distance between the lens L5 of theoptic assembly and photosensor array 202 and the perpendicularitybetween a longitudinal axis through the lenses L1, L2, L3, L4 and thelight receiving surface 204 of the photosensor array 202. The lightreceiving surface 202 is coincident with the image plane of the optic.assembly 300.

The shroud assembly outer shroud 342 and the second support 182 functionto prevent ambient light from impinging on the photosensor array lightreceiving surface 204. When the housing upper and lower portions are141, 142 are assembled, the second support 182 of the two portionsencircle the outer shroud end 343 and the photosensor array lightreceiving surface 204.

As can be seen in FIGS. 9, 12 and 13B, a raised ledge 182 a extendsupwardly from an upper surface 182 c of one side of the second support182. A mating recess 182 c is formed in an upper surface 182 d of theopposite side of the second support 182. When the upper and lowerhousing portions 141, 142 are assembled, the raised ledge 182 a of thelower housing portion 142 is received in a mating recess in an uppersurface of a second support of the upper housing portion 140. The matingrecess of the upper housing portion 141, of course, is identical to therecess 182 c of the lower housing portion 142 as the portions 141, 142are identical in configuration. Similarly, the mating recess 182 c ofthe lower housing portion 142 receives a raised ledge of an uppersurface of the second support of the upper housing portion. The raisedledge of the upper housing portion 141, of course is identical to theraised ledge 182 a of the lower housing portion 142. The interlocking ofthe respective raised ledges 182 a and mating recesses 182 c of thesecond supports 182 of the housing upper and lower portions 141, 142,insure the area between an end 58 a of the shroud assembly 302 and thephotosensor array support 208 is light tight. In addition to preventingambient light from impinging on the photosensor array 202, the secondsupport 182 of the housing upper and lower portions 141, 142 support theshroud assembly 58 and insure that the optical axis A—A through thecenters of the lenses L1, L2, L3, L4 and the pinhole aperture A1 of thespacer member SP1 is perpendicular to the light receiving surface 204 ofthe photosensor array 202 and is also aligned with the center point CPof the photosensor array 202.

The housing lower portion 142 includes two u-shaped latches 190 a, 190 bextending upwardly from the upper edge 164 of the respective side walls152, 156 and two tapered detents 192 a, 192 b in recessed portions ofthe side walls 152, 156 that engage similar detents and latches of theupper portion 141 to seal the mating upper and lower housing portions141, 142. As can be seen in FIG. 8, the two latches 190 a, 190 b engagerespective detents in the housing upper portion 140 corresponding to thedetents 192 a, 192 b of the housing lower portion. Similarly, thedetents 192 a, 192 b are engaged by u-shaped latches of the upperportion. The latches are flexible enough to deflect as they traversetheir respective tapered detents and then snap into engagement positiononce the central openings of the detents pass the opposing detents.

The lower housing 142 includes to apertures 194 a, 194 b (FIGS. 11 and12) which align with identical apertures of the upper portion 141 tofacilitate affixing the module 20 within the housing extending snout 16.The circuit board 460 supports the surface mount illumination LEDsaffixed to the front surface 460 a of the board 460. When the housingupper and lower portions 141, 142 are assembled, ventilation of theelectronic components supported therein including the board cameraassembly circuitry 201 and the targeting and illumination assembly 400is provided by two elongated openings 192, 193 (FIG. 12).

Two slots 195 a, 195 b (as seen in FIGS. 12 and 13B) are disposedbetween the two outerlying portions 175 a, 175 b and portions of theside walls 152, 156 surrounding apertures 194 a, 194 b. One of the slots195 a, 195 b provide a passageway for a plurality of conductive leads196 extending between a conductor 470 affixed to a back side 460 b ofthe circuit board 460 and a conductor 198 affixed to the front side 212of the first circuit board 210 of the board camera assembly 200. Theother of the slots provides a passage for an angled extending portion463 a (FIG. 18) of a flexible printed circuit board 463. The circuitboard 463, typically referred to as “circuit on flex”, electricallyconnects the leads 465 c, 465 d extending rearwardly from the targetingLEDs 464 a, 464 b with circuitry on the circuit board 460 to permitselective energization of the LEDs 464 a, 464 b to aid in aiming thedevice 100 at the target dataform 10. A front section 463 b of theflexible printed circuit board 463 is coupled to the circuitry on thecircuit board 460 through a connector 470 disposed on the back side 460b of the circuit board 460.

Image Processing of the Imaging Assembly 102

In the preferred embodiment of the portable data collection device 100,the photosensor array 202 is part of the modular board camera assembly200 commercially available from such vendors as Sharp or Sony of Japan.Referring to FIGS. 29A and 29B, the camera assembly 200, when activated,generates a composite video signal 260. The board camera assembly 38also includes a clock generator 256, synchronization signal circuitry258 and analog signal processing circuitry 259 for reading illuminationintensity values out of each photosensor of the photosensor array 202and generating the composite video signal 260.

The intensity of light incident on individual pixels or photosensors ofthe photosensor array 202 varies somewhat uniformly from very bright(whitest areas of the image) to very dark (darkest areas of the image).The preferred 2D photosensor array 202 comprises an interlaced 752 by582 matrix array of photodiode photosensors or image pixels (for a totalof 437,664 pixels). The clock generator 256 coupled to a crystaloscillator and generates asynchronous clocking signals to read outcharges accumulating on individual photosensors over an exposure period.The charges on the photosensors are read out through CCD elementsadjacent the photosensor array photosensors. The charges are convertedto a voltage signal 262 wherein temporal portions of the voltage signalrepresent the changes accumulated on each photosensor. One CCD elementis provided for reading out the charges on two photosensors thus tworead outs of the photosensor array comprise one full image frame, theframe being comprised of two interlaced fields.

The camera assembly 200 generates the composite analog video signal 260(FIG. 29A) corresponding to consecutive fields of the image incident onthe photosensor array 202. The video signal 260 is termed “composite”because it includes synchronization signals generated by thesynchronization signal circuitry 258 which correlate portions of thevideo signal to particular photosensors, interspersed among image signalportions wherein the signal magnitude represents charges on individualphotosensors read out from a given row of the photosensor array 202.

The board camera assembly 200 also includes gain control circuitry 264for controlling amplification of the voltage image signal 262 andexposure period control circuitry 266 for controlling a duration of anexposure period of the pixels. Both the exposure period controlcircuitry 266 and the gain control circuitry 264 are controlled byexposure parameters control circuitry 268 including fuzzy logiccircuitry 270.

The synchronization signals 268 generated by synchronization signalcircuitry 258, the clock signal 270, generated by the clock generator256, and the composite video signal 260 are output to signal processingcircuitry 264 on the control and decoder board 252. Because the signaland image processing circuitry 250 is configured to receive a compositevideo signal, it should be appreciated that selection of the boardcamera assembly circuitry 201 for generating the composite video signal260 are not critical to the present invention.

Under the control of a microprocessor 251 mounted on the control anddecoder board 252, the video signal 260 is input to the signalprocessing circuitry 276 along with clocking signals 274 andsynchronization signals 272. The signal processing circuitry 276includes synchronization extractor circuitry which receives the clockingsignals 274 and the synchronization signals 272 and generates signalswhich are coupled to analog to digital converter circuitry (A/Dconverter circuitry) 278 causing the A/D converter circuitry toperiodically digitize the video signal 260. The A/D converter circuitry278 includes an A/D converter generating an 8 bit value representing theillumination incident on a pixel of the array.

Direct memory access (DMA) control circuitry 280 receives thesynchronization signals 272 and clock signals 274 and generates addresssignals 281 coupled to the frame buffer memory 282 to indicate a storagelocation for each value generated by the A/D converter circuitry 278.Data signals 283 representing the values generated by the A/D convertercircuitry 278 are coupled to the frame buffer memory 282.

The microprocessor 251 also controls operation of control and selectioncircuitry 284 and image processing circuitry 285 which are mounted onthe control and decoder board 252. Coupled to the control and selectioncircuitry 284 are the dataform read trigger circuit 126 a which, inturn, is coupled to the dataform reading trigger 126.

The exposure parameters control circuitry 268 which outputs controlsignals 286, 287 to the exposure period control circuitry 266 and thegain control circuitry 264 of the camera assembly 200 and a referencevoltage signal 288 embodying an appropriate set of reference voltagesfor operating the A/D converter 278. The exposure parameters controlcircuitry 268 includes the fuzzy logic circuitry 270 which analyzescaptured frames of data accessed from the frame buffer memory 282. Thefuzzy logic circuitry 270 analyzes a captured frame to determines if thecurrent exposure period of the 2D photosensor array 202, the currentamplification of the video signal 262 by the gain control circuitry 264and the reference voltages used by the A/D converter circuitry 278 areresulting in an “acceptable” captured image frame. If not, the controlsignal 286 is changed to adjust the exposure period of the 2Dphotosensor array 202 and/or the control signal 287 is changed to adjustthe amplification of the video signal 262 and/or the signal 288 ischanged to adjust the operation of the A/D converter circuitry 278.After the adjustment, another captured frame is analyzed by the fuzzylogic circuitry 270 and, if necessary, further adjustments are made inan iterative fashion until the camera assembly 200 produces an“acceptable” captured image. A suitable exposure parameter controlcircuit including fuzzy logic control circuitry is disclosed in U.S.

Pat. No. 5,702,059, issued Dec. 30, 1997, which has previously beenreferenced.

The frame buffer memory 282 is provided to store digital gray scalevalues (represented by line 283 in FIG. 29A) generated by the A/Dconverter circuitry 278 from the composite video signal 260. The grayscale values are processed by image processing circuitry 285. The imageprocessing circuitry 285 includes binarization and zoning circuitry 289,rotation correction circuitry 290, cell extraction circuitry 291 anddecoding circuitry 292. The binarization and zoning circuitry 289,rotation correction circuitry 290, cell extraction circuitry 291 anddecoding circuitry 292 operate under the control of the microprocessor251 as disclosed in U.S. application Ser. No. 08/961,096, filed Oct. 30,1997 now U.S. Pat. No. 5,992,425 Jul. 17, 2000 and entitled “PortableData Collection Device with Binarization Circuitry.” application Ser.No. 08/961,096 is assigned to the assignee of the present invention andis incorporated in its entirety herein by reference.

As can be seen in FIGS. 14 and 29A, the power source 124 is coupled tothe control and decoder board 252 to provide operating power to themicroprocessor 251 and other circuitry mounted on the board and theradio module 140 operating under the control of the microprocessor 251.Power circuitry 293, also operating under the control of themicroprocessor 251 is coupled through a lead 294 to the targeting andillumination assembly 400 and the circuitry 201 of the board cameraassembly 200 to supply power to these components of the imaging assembly102.

As can best be seen in FIGS. 29A and 29B, the imaging assembly 102includes the board camera assembly 200 which is electrically coupled tothe control and decoder board 252. The control and decoder board 252includes the microprocessor 251 and associated circuitry. The circuitryof the imaging assembly 102 may by embodied in software resident in oneor more RAM or ROM memory chips (not shown) mounted on the control anddecoder board 252 and operated by the microprocessor 251. Alternately,the circuitry of the imaging assembly 102 may comprise separateapplication-specific integrated circuitry (ASIC) mounted on the controland decoder board 252.

Decoded dataform data may be stored in the frame buffer memory 282 forlater downloading via the serial port 138 via serial output circuitry296 and buffer memory 297 or transmitted to the radio module 140 for rfcommunication to a remote host computer (not shown).

While the description has described the currently preferred embodimentsof the invention, those skilled in the art will recognize that othermodifications may be made without departing from the invention and it isintended to claim all modifications and variations as fall within thescope of the invention.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclose comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

What is claimed is:
 1. A dataform reader for a portable data collectiondevice, the dataform reader utilizing a single two dimensional imagingassembly adapted to independently image and decode first and secondoverlying dataforms, the first dataform being imaged when illuminated byillumination having a first wavelength and the second dataform beingimaged when illuminated by illumination having a second wavelength, thefirst and second wavelengths being different, the dataform readercomprising: a) the single two dimensional imaging assembly including atwo dimensional photosensor array, the imaging assembly actuatable togenerate a signal representative of an image of a target area of theimaging assembly, the target area image resulting from an illuminationpattern received from the target area; b) the imaging assembly includingsignal and image processing circuitry for processing and decoding animage of a dataform positioned in the target area; c) an optic assemblypositioned with respect to the imaging assembly to focus the reflectedillumination from the target area onto the photosensor array; d) anillumination assembly including a first illumination source energizableto generate illumination having a first range of wavelengths and asecond illumination source energizable to generate illumination having asecond range of wavelengths, the first range of wavelengths includingthe first wavelength and not including the second wavelength and thesecond range of wavelengths including the second wavelength and notincluding the first wavelength, the first and second illuminationsources being positioned to illuminate the target area when actuated; e)control and selection circuitry electrically coupled to the imagingassembly and the illumination assembly to actuate the imaging assemblyand selectively energize the first illumination source to image anddecode the first dataform and to actuate the imaging assembly andselectively energize the second illumination source to image and decodethe second dataform; f) wherein the first illumination sourceilluminates the target area with illumination having a spectral outputcentered about a wavelength in the visible spectrum; and g) wherein thecontrol and selection circuitry deenergizes the second illuminationsource while the first illumination source is energized and deenergizesthe first illumination source while the second illumination source isenergized.
 2. The dataform reader of claim 1 where the secondillumination source illuminates the target area with illumination havinga spectral output centered about a wavelength in the ultravioletspectrum.
 3. The dataform reader of claim 1 wherein the firstillumination source comprises red light emitting diodes.
 4. The dataformreader of claim 1 wherein the first illumination source illuminates thetarget area with illumination having a spectral output centered about awavelength of substantially 660 nanometers.
 5. The dataform reader ofclaim 1 wherein the second illumination source illuminates the targetarea with illumination having wavelengths in the ultraviolet spectrum.6. The dataform reader of claim 5 wherein the second illumination sourceilluminates the target area with illumination having a spectral outputcentered about a wavelength of substantially 254 nanometers.
 7. Thedataform reader of claim 6 wherein the second illumination sourcecomprises an ultraviolet lamp.
 8. The dataform reader of claim 1 whereinthe optics assembly includes a ultraviolet light filter to preventillumination having wavelengths in the ultraviolet spectrum from beingfocused onto the photosensor array.
 9. The dataform reader of claim 1wherein the two dimensional photosensor array, the optics assembly andthe illumination assembly are supported by a modular housing, thephotosensor array being supported within an internal region of themodular housing.
 10. A dataform reader for a portable data collectiondevice, the dataform reader utilizing a single two dimensional imagingassembly adapted to independently image and decode first and secondoverlying dataforms, the first dataform being imaged when illuminated byillumination having a first wavelength and the second dataform beingimaged when illuminated by illumination having a second wavelength, thefirst and second wavelengths being different, the dataform readercomprising: a) the single two dimensional imaging assembly including atwo dimensional photosensor array, the imaging assembly actuatable togenerate a signal representative of an image of a target area of theimaging assembly, the target area image resulting from an illuminationpattern received from the target area; b) the imaging assembly includingsignal and image processing circuitry for processing and decoding animage of a dataform positioned in the target area; c) an optic assemblypositioned with respect to the imaging assembly to focus the reflectedillumination from the target area onto the photosensor array; d) anillumination assembly including a first illumination source energizableto generate illumination having a first range of wavelengths and asecond illumination source energizable to generate illumination having asecond range of wavelengths, the first range of wavelengths includingthe first wavelength and not including the second wavelength and thesecond range of wavelengths including the second wavelength and notincluding the first wavelength, the first and second illuminationsources being positioned to illuminate the target area when actuated; e)control and selection circuitry electrically coupled to the imagingassembly and the illumination assembly to actuate the imaging assemblyand selectively energize the first illumination source to image anddecode the first dataform and to actuate the imaging assembly andselectively energize the second illumination source to image and decodethe second dataform; and f) wherein the signal representative of thetarget area image is a composite video signal and the signal and imageprocessing circuitry further includes: 1) signal processing circuitryreceiving the composite video signal and converting a portion of thesignal corresponding to an image frame into a set of digital datarepresentative of an image of the target area, the set of digital dataincluding a plurality of digital data values corresponding to respectivedifferent image pixels of the imaged target area, each of the pluralityof digital data values comprising a plurality of bits; and 2) digitalsignal processing circuitry selectively actuatable to receive the set ofdigital data generated by the signal processing circuitry, the digitalsignal processing circuitry including binarization and zoning circuitryto: i) convert selected digital data values in the plurality of digitaldata into a set of binary data values, a single bit binary data valuebeing generated for each digital data value; ii) identify a subset ofbinary data values of the set of binary data values corresponding to animage of the target object; and iii) processing the identified subset ofbinary data values to generate a set of output data.
 11. The dataformreader of claim 10 wherein the signal and image processing circuitryfurther includes cell extraction and decoding circuitry selectivelyactuatable to operate on the identified subset of binary data values togenerate decoded dataform data corresponding to an imaged dataform. 12.The dataform reader of claim 10 wherein the imaging assembly furtherincludes a targeting illumination assembly electrically coupled to thecontrol and selection circuitry, the control and selection circuitryperiodically energizing and deenergizing the targeting illuminationassembly to provide targeting illumination to aid in aiming the deviceat a dataform.
 13. The dataform reader of claim 12 wherein the targetingillumination assembly is deenergized when either of the first or thesecond illumination sources are energized.
 14. A portable datacollection device comprising: a) a housing defining an interior region;b) a dataform reader assembly at least partially supported within thehousing interior region, the dataform reader assembly including a singletwo dimensional imaging assembly adapted to independently image anddecode first and second overlying dataforms, the first dataform beingimaged when illuminated by illumination having a first wavelength andthe second dataform being imaged when illuminated by illumination havinga second wavelength, the first and second wavelengths being different,the dataform reader assembly including: 1) the single two dimensionalimaging assembly including a two dimensional photosensor array, theimaging assembly actuatable to generate a signal representative of animage of a target area of the imaging assembly, the target area imageresulting from an illumination pattern received from the target area; 2)the imaging assembly including signal and image processing circuitry forprocessing and decoding an image of a dataform positioned in the targetarea; 3) an optic assembly positioned with respect to the imagingassembly to focus the target area image onto the photosensor array; 4)an illumination assembly including a first illumination sourceenergizable to generate illumination having a first range of wavelengthsand a second illumination source energizable to generate illuminationhaving a second range of wavelengths, the first range of wavelengthsincluding the first wavelength and not including the second wavelengthand the second range of wavelengths including the second wavelength andnot including the first wavelength, the first and second illuminationsources being positioned to illuminate the target area when actuated,the first illumination source generating illumination having a spectraloutput centered about a wavelength in the visible spectrum; and 5)control and selection circuitry electrically coupled to the imagingassembly and the illumination assembly to actuate the imaging assemblyand selectively energize the first illumination source to image anddecode the first dataform and to actuate the imaging assembly andselectively energize the second illumination source to image and decodethe second dataform, the second illumination source being deenergizedwhile the first illumination source is energized and the firstillumination source being deenergized while the second illuminationsource is energized.
 15. The portable data collection device of claim 14wherein the second illumination source illuminates the target area withillumination having a spectral output centered about a wavelength in theultraviolet spectrum.
 16. The portable data collection device of claim14 wherein the first illumination source comprises red light emittingdiodes.
 17. The portable data collection device of claim 16 wherein thefirst illumination source illuminates the target area with illuminationhaving a spectral output centered about a wavelength of substantially660 nanometers.
 18. The portable data collection device of claim 14wherein the second illumination source illuminates the target area withillumination having wavelengths in the ultraviolet spectrum.
 19. Theportable data collection device of claim 18 wherein the secondillumination source illuminates the target area with illumination havinga spectral output centered about a wavelength of substantially 254nanometers.
 20. The portable data collection device of claim 18 whereinthe second illumination source comprises an ultraviolet lamp.
 21. Theportable data collection device of claim 14 wherein the optics assemblyincludes a ultraviolet light filter to prevent illumination havingwavelengths in the ultraviolet spectrum from being focused onto thephotosensor array.
 22. The portable data collection device of claim 14wherein the two dimensional photosensor array, the optics assembly andthe illumination assembly are supported by a modular housing, thephotosensor array being supported within an internal region of themodular housing.
 23. A portable data collection device comprising: a) ahousing defining an interior region; b) a dataform reader assembly atleast partially supported within the housing interior region, thedataform reader assembly including a single two dimensional imagingassembly adapted to independently image and decode first and secondoverlying dataforms, the first dataform being imaged when illuminated byillumination having a first wavelength and the second dataform beingimaged when illuminated by illumination having a second wavelength, thefirst and second wavelengths being different, the dataform readerassembly including: 1) the single two dimensional imaging assemblyincluding a two dimensional photosensor array, the imaging assemblyactuatable to generate a signal representative of an image of a targetarea of the imaging assembly, the target area image resulting from anillumination pattern received from the target area; 2) the imagingassembly including signal and image processing circuitry for processingand decoding an image of a dataform positioned in the target area; 3) anoptic assembly positioned with respect to the imaging assembly to focusthe target area image onto the photosensor array; 4) an illuminationassembly including a first illumination source energizable to generateillumination having a first range of wavelengths and a secondillumination source energizable to generate illumination having a secondrange of wavelengths, the first range of wavelengths including the firstwavelength and not including the second wavelength and the second rangeof wavelengths including the second wavelength and not including thefirst wavelength, the first and second illumination sources beingpositioned to illuminate the target area when actuated; and 5) controland selection circuitry electrically coupled to the imaging assembly andthe illumination assembly to actuate the imaging assembly andselectively energize the first illumination source to image and decodethe first dataform and to actuate the imaging assembly and selectivelyenergize the second illumination source to image and decode the seconddataform; and c) wherein the signal representative of the target areaimage is a composite video signal and the signal and image processingcircuitry further includes: 1) signal processing circuitry receiving thecomposite video signal and converting a portion of the composite videosignal corresponding to an image frame into a set of digital datarepresentative of an image of the target area, the set of digital dataincluding a plurality of digital data values corresponding to respectivedifferent image pixels of the imaged target area, each of the pluralityof digital data values comprising a plurality of bits; and 2) digitalsignal processing circuitry selectively actuatable to receive the set ofdigital data generated by the signal processing circuitry, the digitalsignal processing circuitry including binarization and zoning circuitryto: i) convert selected digital data values in the plurality of digitaldata into a set of binary data values, a single bit binary data valuebeing generated for each digital data value; ii) identify a subset ofbinary data values of the set of binary data values corresponding to animage of the target object; and iii) process the identified subset ofbinary data values to generate a set of output data.
 24. The portabledata collection device of claim 23 wherein the signal and imageprocessing circuitry further includes cell extraction and decodingcircuitry selectively actuatable to operate on the identified subset ofbinary data values to generate decoded dataform data corresponding to animaged dataform.
 25. The portable data collection device of claim 23wherein the imaging assembly includes a targeting illumination assemblyelectrically coupled to the control and selection circuitry, the controland selection circuitry periodically energizing and deenergizing thetargeting illumination assembly to provide targeting illumination to aidin aiming the device at a dataform.
 26. The portable data collectiondevice of claim 25 wherein the targeting illumination assembly isdeenergized when either of the first or the second illumination sourcesare energized.